1. What is a cell?
Each cell has a plasma membrane, cytoplasm, and a nucleus (in eukaryotic cells) or a nucleoid (in prokaryotic cells)
Surface-to-volume ratio limits cell size

2. What is cell theory? Three key points of the cell theory:
organisms consist of one or more cells
smallest unit that retains the capacity for life
arises from the growth and division of another cell

3. How do we see cell?
Different microscopes use light or electrons to reveal details of cell shapes or structures

4. What is the structure of membrane?
Each cell membrane is a boundary (lipid bilayer)
controls flow of substances across it
Fluid mosaic model
Membrane is composed of phospholipids, sterols, proteins, and other components
Phospholipids drift within the bilayer
extracellular
environment
one layer
of lipids
membrane
protein
one layer
of lipids
cytoplasm

5. What are membrane proteins?
Many proteins are embedded in or attached to cell membrane surfaces
Receptors, transporters, communication proteins, and adhesion proteins
Plasma (outer) membrane also incorporates recognition proteins

6. What are prokaryotic cells?
Bacteria and archaeans
The simplest cells
The groups with greatest metabolic diversity
Biofilms
Shared living arrangements of prokaryotes
Cell wall
Surrounds plasma membrane
Flagella
Used for motion
Pili
Protein filaments used for attachment
“Sex” pilus transfers genetic material

7. What are eukaryotic cells?
Start with a nucleus and other organelles
Carry out specialized functions inside a cell

8. Let’s explore the nucleus
Nucleus separates DNA from cytoplasm
Chromatin (all chromosomal DNA with proteins)
Chromosomes (condensed)
Nucleolus assembles ribosome subunits
Nuclear envelope encloses nucleoplasm
Pores, receptors, transport proteins

9. What is the endomembrane system ?
Endoplasmic reticulum (ER)
An extension of the nuclear envelope
RER modifies new polypeptide chains
SER makes lipids; other metabolic functions
Golgi bodies
Further modify polypeptides
Assemble lipids

10. What else does it do? Vesicles
Endocytic and exocytic: Transport or store polypeptides and lipids
Peroxisomes: Digest fatty acids and amino acids; break down toxins and metabolic by-products
Lysosomes: Intracellular digestion (animals)
Central vacuole: Storage; fluid pressure (plants)

11. Other organelles! Mitochondria Chloroplasts
Break down organic compounds by aerobic respiration (oxygen-requiring)
Produce ATP
Chloroplasts
Produce sugars by photosynthesis

12. Cell wall only in plant cells!
prokaryotes, protists, fungi, all plant cells have cell wall around their plasma membrane
Protects, supports, maintains cell shape
Primary and secondary cell walls
Plasmodesmata across cell walls connect plant cells

13. Cytoskeleton only in animal cells!
Microtubules
Microfilaments
Intermediate filaments
Organizes
Moves cell parts
Reinforces cell shape
Interactions between
motor proteins
microtubules
cilia, flagella,
pseudopods
can move cell

14. Other features! Plant cuticle
Protective surface secretion, limits water loss
Connect cells of animals
adhering junctions
tight junctions
gap junctions

15. Plant vs animal cell